#!/bin/sh
#
echo "#!/bin/sh" > customize.$$
echo "sed \\" > customize.$$
chmod +x customize.$$

################################################################
# find a working perl:
#
for i in /usr/bin/perl /usr/local/bin/perl /usr/bin/perl5 /usr/local/bin/perl5
do
    if $i -e 'exit ($] < 5.000)'
    then
	echo $i works
	perl="$i"
	break
    fi
done
if [ -z "$perl" ]
then
    could not find a working perl command, sorry.
    exit 1
fi
echo "  -e 's,@@@perl@@@,$perl,g' \\" >> customize.$$


################################################################
# find a diff which understands --changed-group-format
# and related options (like gnu diff)
#
echo 'a
b
c' > diff_format-test.$$.1
echo 'a
B
c' > diff_format-test.$$.2

wanted="<b
=B
>"
for i in /usr/bin/diff /usr/local/bin/diff
do
    a="`$i --unchanged-group-format='' --changed-group-format='<%<=%>>' diff_format-test.$$.1 diff_format-test.$$.2`"
    echo "$a"

    if [ "x$a" = "x$wanted" ]
    then
	echo $i works
	diff_format="$i"
    fi
done
if [ -z "$diff_format" ]
then
    echo could not find a working diff_format command, sorry.
    exit 1
fi
echo "  -e 's,@@@diff_format@@@,$diff_format,g' \\" >> customize.$$
rm diff_format-test.$$.?


################################################################
# finish
#	Add trailing newline and rename temp file to final name
#
echo  >> customize.$$

mv customize.$$ customize